Don't reset random state in random::init() if already seeded.

include/random.hpp

@@ -28,15 +28,19 @@ Example:
 	double r = normal(rng);
 */
 struct Xoroshiro128Plus {
-	uint64_t state[2];
+	uint64_t state[2] = {};
 
-	Xoroshiro128Plus(uint64_t s0 = 1, uint64_t s1 = 0) {
+	void seed(uint64_t s0, uint64_t s1) {
 		state[0] = s0;
 		state[1] = s1;
 		// A bad seed will give a bad first result, so shift the state
 		operator()();
 	}
 
+	bool isSeeded() {
+		return state[0] || state[1];
+	}
+
 	static uint64_t rotl(uint64_t x, int k) {
 		return (x << k) | (x >> (64 - k));
 	}

src/random.cpp

@@ -16,9 +16,13 @@ static std::atomic<uint64_t> threadCounter {0};
 
 
 void init() {
+	// Don't reset state if already seeded
+	if (rng.isSeeded())
+		return;
+
 	struct timeval tv;
 	gettimeofday(&tv, NULL);
-	rng = Xoroshiro128Plus(uint64_t(tv.tv_sec) * 1000000 + tv.tv_usec, threadCounter++);
+	rng.seed(uint64_t(tv.tv_sec) * 1000 * 1000 + tv.tv_usec, threadCounter++);
 	// Shift state a few times due to low seed entropy
 	for (int i = 0; i < 4; i++) {
 		rng();